The presence of people in a room can change the local microenvironment of the space, for example raising temperature, or altering relative humidity, carbon dioxide (CO2) or volatile organic compound (VOC) levels. This affect can have significant impacts on certain environments that commonly host large numbers of visitors.
For example, a museum has to preserve objects of art for very long periods of time—several hundreds of years—and usually contains multiple galleries where large numbers of people can gather to appreciate the art pieces. Some works of art are very susceptible to environmental variations, and some of those variations can be caused by the presence of large groups of people affecting the microenvironment in the museum. While air conditioning systems are often in place to control the temperature, humidity, etc. they are typically only able to react to changes in the environment which have already occurred. By that time, the movement of visitors through the museum may have already changed, thus warranting a different set of adjustments. Additionally, the objects may be packaged in an enclosure to protect them from environmental fluctuations—but these will alter the aesthetic appreciations of art objects and is usually a very expensive procedure. Therefore, being able to track, manage, and anticipate the movement of visitors through a museum such that proactive measures can be taken to adjust for the visitors' impact on the environment would be desirable.
Further, the presence of visitors in an environment can also alter the chemical and biological composition of the air by dispersing disease-causing bacteria into the air. Such is the case for the risk of spreading flu in any place where multiple people gather like: athletic facilities, health care facilities, dormitories, schools, daycare settings, military barracks, prisons, museums, etc. In environments like hospitals, special precautions can be taken to reduce the exposure risk—like isolating patients. However, such actions are very expensive. Another, technique to reduce risks is to control the exposure of patients to visitors whose presence may increase a risk/hazard of infection to the patients. Therefore, being able to track and manage visitors to a hospital so as to be able to control an impact the visitors have on the environment would be desirable.